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In computational auditory scene analysis, the accurate estimation of binary mask or ratio mask plays a key role in noise masking. An inaccurate estimation often leads to some artifacts and temporal discontinuity in the synthesized speech. To overcome this problem, we propose a new ratio mask estimation method in terms of Wiener filtering in each Gammatone channel. In the reconstruction of Wiener filter, we utilize the relationship of the speech and noise power spectra in each Gammatone channel to build the objective function for the convex optimization of speech power. To improve the accuracy of estimation, the estimated ratio mask is further modified based on its adjacent time–frequency units, and then smoothed by interpolating with the estimated binary masks. The objective tests including the signal-to-noise ratio improvement, spectral distortion and intelligibility, and subjective listening test demonstrate the superiority of the proposed method compared with the reference methods.

There is a lack of standardization in sperm cryopreservation of aquatic organisms and, thus, a necessity of more accurate investigations in all steps of this process. In this study, the effects of sperm dilution ratio on post-thaw sperm quality of Prochilodus lineatus were evaluated. Sperm was diluted in a standard freezing medium (glucose and methyl glycol) at four different ratios (sperm to final volume = 1:5, 1:10, 1:50 or 1:100), frozen in a nitrogen vapour vessel at –170°C and then stored in liquid nitrogen vessel at –196°C. Post-thaw motility rate and velocities (curvilinear = VCL; average path = VAP; straight line = VSL) were determined using a Computer-Assisted Sperm Analyzer (CASA) at 10 and 40 s post-activation. The highest motility rates were observed when sperm was frozen at a ratio of 1:5 (76%) and 1:10 (75%). The highest VCL (225 μm/s) and VAP (203 μm/s) were observed at a ratio of 1:10, while VSL was similar among samples frozen at 1:5, 1:10 and 1:50 (97–124 μm/s). When those parameters were evaluated again 30 s later, motility decreased significantly in samples frozen at a ratio of 1:5 (57%) and 1:10 (61%), while velocities decreased significantly in all samples regardless of dilution ratio (75–85 μm/s of VCL, 38–53 μm/s of VAP and 25–39 μm/s of VSL). P. lineatus sperm should be frozen at a ratio of 1:10, where both the number of loaded sperm per straw and the post-thaw quality are maximized.

The adaptive significance of variation in sperm phenotype is still largely unknown, in part due to the difficulties of observing and measuring sperm movement in its natural, selective environment (i.e., within the female reproductive tract). Computer-assisted sperm analysis systems allow objective and accurate measurement of sperm velocity, but rely on being able to track individual sperm, and are therefore unable to measure sperm movement in species where sperm move in trains or bundles. Here we describe a newly developed computational method for measuring sperm movement using Fourier analysis to estimate sperm tail beat frequency. High-speed time-lapse videos of sperm movement within the female tract of the neriid fly Telostylinus angusticollis were recorded, and a map of beat frequencies generated by converting the periodic signal of an intensity versus time trace at each pixel to the frequency domain using the Fourier transform. We were able to detect small decreases in sperm tail beat frequency over time, indicating the method is sensitive enough to identify consistent differences in sperm movement. Fourier analysis can be applied to a wide range of species and contexts, and should therefore facilitate novel exploration of the causes and consequences of variation in sperm movement.

Sperm characteristics of scallops have not been well described in the scientific
literature. The effects of sperm release technique (thermal shock versus serotonin
injection), of sperm collection technique (testis sampling versus serotonin injection), of
sperm sampling location along the genital tract, of in vitro sperm maturation, and of time
post activation on scallop sperm characteristics were assessed in the present work.
Whatever sperm release technique used, no significant differences were observed regarding
the percentage of motile spermatozoa and the velocity of the average path (VAP). Compared
to testicular sperm, a higher percentage of motile spermatozoa, VAP and intracellular
adenosine triphosphate (ATP) content were observed for sperm shed after serotonin
injection. From the distal part of testes up to the gonopore, an increase of the
percentage of motile spermatozoa and VAP was assessed, suggesting a sperm ‘maturation
process’ along the genital ducts. A higher increase in the percentage of motile sperm was
recorded during a 5 min incubation of testicular sperm in seawater containing 2 mM
serotonin and seawater containing 10 mM caffein compared to seawater (control). In
addition, a higher VAP was assessed, incubating testicular sperm in caffein, compared to
control or serotonin. Then, the percentage of motile spermatozoa, VAP and intracellular
ATP content exhibited a progressive reduction during the 10 h swimming period. Mean values
of the percentage of motile spermatozoa, VAP, sperm track linearity (LIN) and
intracellular ATP content recorded at the beginning of the movement period for sperm
samples collected after intragonadal serotonin injection, were 82 ± 7%,
162 ± 15μm s-1, 0.33 ± 0.12 and 212 ± 133 nmol
× 10-9 spermatozoa (n = 9 males), respectively. The present
study confirms the existence of a sperm “maturation process” along scallop genital ducts.
In addition, the cessation of scallop sperm movement can be explained by the exhaustion of
ATP content at the end of the movement phase.

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